1. Field of the Invention
The invention relates to the separation of metal from a coprecipitate by contacting the coprecipitate with a Clostridium sp. ATCC No. 53464.
2. Description of the Related Art
Metals such as transition metals and heavy metals are present in soils, sediments and energy wastes. There is a significant input of metals into terrestrial and aquatic ecosystems from solid waste disposal and from atmospheric deposition of anthropogenic pollutants. Many of these metals are toxic, for example, arsenic, cadmium, cobalt, copper, mercury, nickel, lead, selenium, zinc and others.
A method for scavenging metals from power plant wastestreams using amorphous iron oxyhydroxide (Fe(OH).sub.3) has been described by J. O. Leckie, et al., Adsorption/Coprecipitation of Trace Elements From Water With Iron Oxyhydroxide, Electric Power Research Report CS-1513, Palo Alto, Calif., 1980. Naturally occurring oxides may act as sink for metals in the terrestrial and aquatic environments. A method using ferric iron from colloidal ferric hydroxide, FeCl.sub.2 and Fe.sub.2 (SO.sub.4).sub.3 as a coprecipitant and laurylammonium chloride as a collector has been described for coprecipitating arsenic from geothermal brine of high ionic strength ( E. H. DeCarlo and D. M. Thomas, Environ. Sci. Technol. 19, 538-544 (1985)).
U.S. Pat. No. 4,519,913 to Baldwin et al. and U.S. Pat. No. 4,519,912 to Kauffman et al. describe methods for removing certain ions from aqueous solutions by contacting the solutions with bacteria of the genus Clostridium to convert soluble ions to an insoluble form. Kauffman et al. utilize both a Clostridium and a Desulfovibrio or Desulfotomaculum. However, coprecipitation and subsequent solubilization of ions are not suggested.
U.S. Pat. No. 3,829,377 to Hashimoto et al. discloses using Clostridium bacteria in conjunction with a C.sub.1-3 hydrocarbon to denitrify water. U.S. Pat. No. 4,510,243 to Haga et al. discloses the use of Clostridium bacteria for treating cellulose-containing water.
U.S. Patent Nos. 4,826,602, 4,789,478, 4,732,681, 4,728,427 and 4,522,723 describe processes for reducing ionic species in aqueous solutions using various bacterial microorganisms. None of these suggests coprecipitation followed by solubilization.
U.S. Pat. No. 4,758,345 to Francis et al. describes a method for the dissolution of lead oxide in industrial wastes through the action of acids produced by Clostridium sp. ATCC No. 53464. The disclosure is specifically directed toward solubilizing lead oxide through the production of organic acids and the lowering of the pH and no coprecipitation is suggested nor is the use of direct bacterial enzymatic action to solubilize a coprecipitate suggested.
It is therefore an object of the invention to provide a method for separating metals from a coprecipitate. It is a further object to remove metal from fluids by coprecipitating the metal and then separating the metal from the coprecipitate. It is another object of the invention to provide a method for microbial remobilization of metals coprecipitated with coprecipitating agents.